Contraction of Skeletal Muscle
Physiologic anatomy of Skeletal Muscle Skeletal Muscle Fibre Myofibrils are composed of Actin and Myosin filaments: Each muscle fiber consists of millions of myofibrils, and each myofibril is composed of 1500 myosin filaments and 3000 actin filaments lying side by side. These are large polymerised protein molecules that are responsible for muscle contraction. The tick filaments myosin and the the thin filaments actin: Light and dark bands: The myosin and the actin filaments partially interdigitate and thus cause light and dark bands. The light bands contain only actin filaments and are called I Bands . The dark bands contain myosin filaments as well as the ends of actin filaments , where they overlap the myosin, and are called A bands. Cross-Bridges: The small projections from the sides of myosin filaments are cross-bridges. They protrude from the surfaces of the myosin filament along its entire length except the centre. Interaction between these cross bridges